1. Field of the Invention
The present invention relates to a flip-chip semiconductor device and its manufacturing method.
2. Description of the Related Art
In a first prior art method for manufacturing a flip-chip type semiconductor device (see: JP-A-6-29334), first, a flip-chip type semiconductor chip having metal bumps is faced down and then is mounted on an interposer substrate having pad electrodes, so that the metal bumps are in contact with respective ones of the pad electrodes. Next, thermosetting resin including silica or alumina is injected into a gap between the semiconductor chip and the interposer substrate, so that an under-fill resin layer is formed therebetween. Next, the interposer substrate is subjected to ultrasonic vibration, in order to eliminate voids from the under-fill resin layer. Finally, a heating operation is performed upon the under-fill resin layer, so that the under-fill resin layer is hardened. This will be explained later in detail.
In the above-described first prior art method, however, since under-fill resin is injected into a gap after such a gap is formed between the semiconductor chip and the interposer substrate, it is difficult to completely inject under-fill resin into the gap due to the fact that the gap is very narrow.
In a second prior art method for manufacturing a flip-chip type semiconductor device (see: JP-A-10-335373), first, thermosetting resin including silica or alumina is coated on an interposer substrate having pad electrodes, so that an under-fill resin layer is formed thereon. Next, a flip-chip type semiconductor chip having metal bumps is faced down and then is mounted on the interposer substrate, so that the metal bumps are in contact with respective ones of the pad electrodes. Next, the semiconductor chip is subjected to ultrasonic vibration, so that a solid-phase diffusion occurs at the contact portions between the metal bumps and the pad electrodes. Finally, a heating operation is performed upon the under-fill resin layer, so that the under-fill resin layer is hardened. This also will be explained later in detail.
In the above-described second prior art method, however, since an uneven surface of the under-fill resin layer is covered by the semiconductor chip, a large void is generated within the under-fill resin layer, which deteriorates the adhesive characteristics between the semiconductor chip and the interposer substrate.
It is an object of the present invention to suppress the deterioration of the characteristics of a flip-chip type semiconductor device.
According to the present invention, in a flip-chip type semiconductor device including a semiconductor chip having metal bumps on one surface thereof, an interposer substrate having pad electrodes on one surface thereof, and an under-fill resin layer filled into a gap between the semiconductor chip and the interposer substrate where the metal bumps are in contact with the pad electrodes, the under-fill resin layer has a number of split voids therein.
Also, in a method for manufacturing a flip-chip type semiconductor device, an under-fill resin layer is coated on an interposer substrate having pad electrodes thereon. Next, a semiconductor chip having metal bumps is mounted on the interposer substrate, so that the metal bumps oppose the pad electrodes. In this case, the semiconductor chip is subjected to ultrasonic vibration, after the metal bumps are in contact with the under-fill resin layer and before the metal bumps are in contact with the pad electrodes.